Choosing the Right Car and Platform for Great Car Audio
The car you start with sets the ceiling for how good a car audio system can sound. Peter Steinbacher of Pssound teaches that where the speakers can go (above all the midbass, the speaker that gives music its punch), how quiet and rigid the body is, and how the cabin handles bass matter more than the equipment budget. His core idea: choose the car with the system in mind, and strip it before you plan anything.
The short version
The car sets the ceiling for the sound, so choose it with the system in mind.
Peter says midbass is the hardest part of any build, so pick a car where it can be done easily.
Peter's first choice is a recent Mercedes with 8" midbass drivers in the firewall, BMW is second, and he advises against pickups.
Look behind the panels before you buy: firewall depth, kick space and the factory audio package all matter.
A quiet, rigid, short cabin makes everything easier.
Peter says to enjoy the system now and worry about resale when you sell, and leased cars can be done reversibly.
Why the car sets the ceiling
Peter's starting point is blunt: "You can only work with the car, you can't work against it." (watch) Some cars will never be great platforms (the car's layout, body and factory speaker positions) and always need extra work, so choosing with the system in mind can spare you hundreds of hours of labour. Pssound works in this order: what the car allows, then the speakers, then what budget and time can achieve.
Location beats price. People who heard his S-Class asked what midbass drivers it used. The answer was the ones the factory fitted, in the factory position.
He says midbass is the hardest part of every car, so start with one where it can be done easily (watch). Our midbass guide explains why.
The platform shows in the hours. A Kia took 4–5 days for all six front speakers, while speakers alone take 15–20 days in some cars. The C43 AMG took about 175 labour hours, against 250–300 for comparable cars needing custom midbass, a front sub and boot work (watch).
Good factory locations let you skip custom fabrication and spend on speakers, amplification or DSP (the digital processor that tunes the sound). Poor ones can make labour balloon. See our costs guide.
Hardly anyone chooses a car by its speaker locations: Peter says only about one buyer in a thousand does.
Why Mercedes is his first choice
Peter's standing advice is a recent Mercedes with 8" drivers up front. In these cars the midbass speaker sits in the firewall (the metal wall between the engine bay and the cabin), not in a door. That wall is rigid, so even the stock drivers hit hard up front with no buzzes or rattles (watch). Swapping the speakers is, he says, about a two-hour job. His line: "If you don't have budget for the fabrication, get a Mercedes." (watch)
He says that in most Mercedes models (not every one) the firewall spot is so good that a budget driver, fitted properly, outperforms an expensive driver in a door (watch). No AMG needed: a second-hand C-Class with a smaller engine and more miles will do.
The S-Class (from about 2014), C-Class and E-Class (from 2016) share speaker mounting and sizes: midbass in the firewall by the driver's pedals, midrange on top of the door card, tweeter in the sail (the small panel at the front corner of the door).
A primary reason he bought his own demo S-Class was its deep spare-wheel well, which takes a true IB sub (infinite baffle: the sub sits in a wall and the space behind it acts as its box).
Not every Mercedes is easy. The 2017 B-Class was far harder than expected, so Peter tells owners to get ready for double the work, and the G-Class, a glassy box with no room for a front sub, is really not ideal for high-end listening.
Locations are slipping. In 2026 Peter and judge Horst Starke noted that the new W206 C-Class moved its mid lower, and that factory locations are getting less and less ideal (watch).
BMW, Mini and other cars that work
Peter's view of BMW has changed. In 2019 he was against BMW platforms; by 2022 he called BMW a fantastic platform needing no crazy custom work; in 2025 it is his second choice after Mercedes. The bass driver is in the floor rather than the door, which brings its own challenges but gives the punchy feel and 8" drivers (watch).
The layout, shared by almost all BMWs: a very flat 8–9" bass driver under each front seat, a 4" in the door card (usually full range, so short on detail) and a tweeter in the sail panel or mirror back.
A BMW that still looks stock can sound very good with a three-way setup, but only if it is active (each speaker gets its own amplifier channel) and tuned with a DSP. The catch is a slightly lower stage, because the midrange sits low in the door.
Newer is not always simpler. The G20/G21 3 Series door mid sits on the inner skin and the usual access holes are sealed. People online drill through to find the glass bolts; Pssound will not (watch).
A Mini is a BMW-group car and very easy to build a good system in (watch). Its door midrange sits higher than BMW's, and a Clubman has room under the boot floor for an IB sub and three amps.
Others help too: a Kia's dash locations sit at an ideal angle for midrange, and many Toyotas and Lexus have the mid and tweeter up on the dash, which makes a high stage easier.
Check the car before you buy
Peter's warning: a quick look at the panels tells you little, because you only learn what a car allows once the dash and trims are out. One client bought a Ford Focus ST for a competition build because the dash looked roomy and the kicks looked decent. Stripped, none of it was practical, and doing it right needed an extortionate budget (watch).
Check how far the firewall comes in under the dash, which he says people never see. In the Focus ST500 it came about 5" into the cabin, leaving roughly 1" below the dash top, so its big flat dash had no space underneath (watch).
Room in the kicks (the lower side panels by your feet) is rare. Most cars have almost none, and kick midbass is especially hard in right-hand-drive cars, while big American cars and the Mercedes CLK have plenty (watch). A clutch pedal can also cost you the kick: the Insignia's box fitted only because that car had none.
The factory audio package matters, not just the model. The base 2-way Audi A6 C7 had a tweeter on the dash but no mid-position speaker or wiring. A BMW with the Harman Kardon option adds tweeter locations and an easy-to-tap factory amp.
Quiet, rigid cabins and cabin shape
A high-end listening experience starts with the right environment. Peter's advice is to begin with a car that is quiet from the factory and add treatment on top; the S-Class gave him the best starting point (watch). He agrees an entry-level hatch like the Suzuki Swift is the wrong start for a really quiet car. Our deadening guide covers the treatment itself.
A few premium cars are quiet enough that treatment can be limited to the boot (where the bass plays) and the doors, if speakers go there. His examples are the Mercedes S-Class, Audi A8, BMW 7 Series and high-end Lexus. It is far less work, but you pay more for the car.
Rigidity counts too. Peter calls a Mercedes E-Class a great platform partly because the car is more rigid, and older cars can be built better: the 22-year-old BMW E39 still has nothing that buzzes or rattles.
Short cabins favour midbass. The Suzuki Swift, with true-IB midbass in the kicks, is still the craziest midbass he has heard: a short cabin with drivers closer to you, heavy deadening and a rigid body give instant chest kick at low level, with only about 2 mm of cone movement (watch).
Pickups, vans, sports cars and EVs
Peter's advice on pickups is plain: if you want an amazing sound system, do not buy one. The cabin is poor for sound, the speaker locations are bad and it means a huge amount of work (watch). The VW Amarok he worked on took two years and is a project that never ends.
Vans, Peter says, are equally challenging: they leave the factory very rattly and need a fair amount of treatment first. In a VW Transporter the hard part is real bass, because the cabin is short. Where a bulkhead (a wall) stands behind the seats, a sub playing through it acts like a front sub, so it can play higher up the range without the problems long cars have above 60–70 Hz.
The Nissan GT-R R35 is one of the most challenging platforms, needing real work where current BMWs and Mercedes take plug-and-play speaker swaps. His view of its hidden space changed: in 2024 he saw no room anywhere, but by 2025 he had found big cavities under the floor on both sides, enough for enclosures of about 10 L (watch).
Peter says an EV is the best platform for power supply. The audio runs at 12 V (13.5 V) while the Taycan's main battery is 800 V, and playing the previous system for 8 hours used 4% of that battery (watch).
Cutting, leasing and warranty
Owners of newer cars often say they cannot cut the car because they must keep its value. Peter understands but disagrees. He asks when they plan to cut it: in 5 or 10 years, when it is going to cost less? By then they could have enjoyed the system for years, so enjoy it now and worry about it when you sell (watch).
If you plan to sell soon, do not cut. He removes the speakers from his own builds before selling them.
He compares cutting kicks to building a race car. A cut through the inner wing can be welded back, or patched and repainted so nobody would notice, and replacement carpet from a breaker (a scrapyard) is doable. A footwell front-sub cut hides under the mat, and the box can be removed to return the car to stock.
A leased car limits the work. The first Taycan was leased, so the midbass stayed in the doors and nothing was cut, not even the carpet, and the car went back to factory within a day.
Warranty fears have faded. In 2021 the team kept the first Taycan build quiet because a manufacturer does not want anyone touching a brand-new car under warranty. By 2024 Porsche had seen the system, did not complain and liked it, and three years of warranty went well (watch).
Common mistakes to avoid
Falling for a car first and asking later what can be done in it. The price is paid in labour hours.
Judging a car from a quick look at the panels. What sits behind them decides what you can build.
Assuming plug and play means easy. The B-Class and the G20/G21 3 Series both looked simple and were not.
Starting with a noisy, rattly entry-level car or a van and expecting a quiet, high-end result without proper treatment.
Buying an expensive car you would be afraid to cut. If audio matters most, Peter says to buy something cheaper and reliable and spend on the installation.
Watch Peter explain it
This is an independent, plain-English summary of Peter Steinbacher's public YouTube videos, written by VA3 Car Studio. It is not affiliated with or endorsed by Pssound. The links jump to the moment in each video where he makes the point.
Part of our series: Car audio lessons from Pssound, start here
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